docs: def get_geophysical_variables(ds):
      '''
      Returns a list of variable names for the variables detected as geophysical
      variables.
  
      :param netCDF4.Dataset nc: An open netCDF dataset
      '''
  
      parameters = []
      for variable in ds.variables:
          if is_geophysical(ds, variable):
              parameters.append(variable)
      return parameters